1. Technical Field
The invention relates to a method for the reconditioning of a friction pair in a service brake of the drum or disc brake type forming part of a brake system of a vehicle, which in addition to the said service brake comprises one or more auxiliary brakes and a control system for distributing the requested brake power between the said service brake and auxiliary brakes. The invention also relates to a vehicle containing an arrangement for the reconditioning of a friction pair according to the pre-characterizing part of claim 19.
2. Background Art
In addition to the usual service brakes in the form of disc or drum brakes, use is made, in modern, heavy vehicles, of a number of auxiliary brakes or secondary brake units, in the form, for example, of hydraulic or electric retarders and engine brakes. Auxiliary brakes are used, where appropriate, to recover braking energy as useful energy and to prolong the life of service brakes. Vehicles equipped with both service brake and auxiliary brakes or secondary brake unit utilize either manual application of service brake and auxiliary brakes or secondary brake units, or automatically controlled application of service brake and auxiliary brakes or secondary brake unit, where a control unit selects the distribution of brake power between service brake and auxiliary brakes or secondary brake unit as a function of the operating condition of the vehicle. An example of a system for controlling a brake system comprising a service brake and an auxiliary brake is described in EP 974 505. The control system ensures that the auxiliary brake is used in each application of the brakes. In a preferred embodiment, the auxiliary brake is used to such an extent that the risk of glazing is reduced. The term glazing refers to the formation of compounds with lower friction than the nominal friction. These compounds can occur when the temperature of the brake disc or the brake drum becomes too low during a large proportion of the brake applications.
One problem with vehicles using a control system according to EP 974 505 and other vehicles currently encountered, in which the brake power is distributed manually or automatically between service brakes and auxiliary brakes or secondary brake unit, or sometimes also with vehicles having no auxiliary brakes or secondary brake unit, is that the service brakes are not used sufficiently. This leads to a risk of rusting or the formation of dirt deposits on the brake disk or brake drum and the aforementioned glazing. The occurrence of rusting and dirt deposits means that the friction of the brake disc or brake drum is reduced, which reduces the efficiency of the brake system.
At high temperature, rust can be converted into a very wear-resistant phase. If the rust is unevenly distributed, this leads to variations in thickness and variations in friction along the circumference. In addition to wear-resistant iron oxides, martensite may also be formed at high temperature. Martensite is hard, brittle and wear-resistant. There is therefore a risk of incipient cracks, uneven wear and variations in thickness and friction should the brakes become overheated.